U.S. patent application number 12/938419 was filed with the patent office on 2012-03-15 for rotor for motor.
Invention is credited to Hung Jen CHUANG, Alex HORNG, Duo-Nian SHAN.
Application Number | 20120062050 12/938419 |
Document ID | / |
Family ID | 45805957 |
Filed Date | 2012-03-15 |
United States Patent
Application |
20120062050 |
Kind Code |
A1 |
HORNG; Alex ; et
al. |
March 15, 2012 |
Rotor for Motor
Abstract
A rotor for a motor includes a shaft having an outer periphery
with an engaging portion. At least one coupling member includes an
engaging hole. The shaft extends through the engaging hole of the
at least one coupling member. The at least one coupling member is
engaged with the engaging portion of the shaft by tight coupling. A
plastic magnet envelops the shaft and the at least one coupling
member by injection molding. The at least one coupling member
prevents the plastic magnet from disengaging from the shaft,
providing enhanced engaging effect while reducing structural
complexity and enhancing assembling convenience.
Inventors: |
HORNG; Alex; (Kaohsiung,
TW) ; CHUANG; Hung Jen; (Kaohsiung, TW) ;
SHAN; Duo-Nian; (Kaohsiung, TW) |
Family ID: |
45805957 |
Appl. No.: |
12/938419 |
Filed: |
November 3, 2010 |
Current U.S.
Class: |
310/43 |
Current CPC
Class: |
H02K 1/28 20130101; H02K
1/30 20130101; H02K 1/2733 20130101; H02K 15/12 20130101 |
Class at
Publication: |
310/43 |
International
Class: |
H02K 1/04 20060101
H02K001/04 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 13, 2010 |
TW |
099130875 |
Claims
1. A rotor for a motor comprising: a shaft including an outer
periphery having an engaging portion; a first coupling member
including an engaging hole, with the shaft extending through the
engaging hole of the first coupling member, with the first coupling
member engaged with the engaging portion of the shaft by tight
coupling; and a plastic magnet enveloping the shaft and the first
coupling member by injection molding.
2. The rotor for a motor as claimed in claim 1, with an outer
periphery of the first coupling member including a positioning
portion such that the first coupling member has non-circular cross
sections perpendicular to an axial direction of the first coupling
member, with the plastic magnet engaged with the positioning
portion.
3. The rotor for a motor as claimed in claim 2, with the
positioning portion including a plurality of recessed portions
formed on the outer periphery of the first coupling member.
4. The rotor for a motor as claimed in claim 2, with the
positioning portion including a plurality of protruded portions
formed on the outer periphery of the first coupling member.
5. The rotor for a motor as claimed in claim 2, with the
positioning portion including a plurality of rugged faces formed on
the outer periphery of the first coupling member.
6. The rotor for a motor as claimed in claim 1, with the plastic
magnet integrally enveloping an intermediate portion of the
shaft.
7. The rotor for a motor as claimed in claim 1, further comprising:
a second coupling member including an engaging hole, with the shaft
extending through the engaging hole of the second coupling member,
with the second coupling member engaged with the engaging portion
of the shaft by tight coupling, with the second coupling member
spaced from the first coupling member in an axial direction of the
shaft.
8. The rotor for a motor as claimed in claim 7, with the second
coupling member being a metal ring having hardness smaller than the
shaft.
9. The rotor for a motor as claimed in claim 1, with the first
coupling member being a metal ring that are less hard than the
shaft.
10. The rotor for a motor as claimed in claim 1, with the engaging
portion of the shaft having an outer diameter perpendicular to an
axial direction of the shaft, with the engaging hole of the first
coupling member having a diameter perpendicular to the axial
direction of the shaft, with the diameter of the engaging hole of
the first coupling member smaller than the outer diameter of the
engaging portion of the shaft.
11. The rotor for a motor as claimed in claim 7, with the engaging
portion of the shaft having an outer diameter perpendicular to an
axial direction of the shaft, with the engaging hole of the second
coupling member having a diameter perpendicular to the axial
direction of the shaft, with the diameter of the engaging hole of
the second coupling member smaller than the outer diameter of the
engaging portion of the shaft.
12. The rotor for a motor as claimed in claim 7, with an outer
periphery of the second coupling member including a positioning
portion such that the second coupling member has non-circular cross
sections perpendicular to an axial direction of the second coupling
member, with the plastic magnet engaged with the positioning
portion.
13. The rotor for a motor as claimed in claim 12, with the
positioning portion including a plurality of recessed portions
formed on the outer periphery of the second coupling member.
14. The rotor for a motor as claimed in claim 12, with the
positioning portion including a plurality of protruded portions
formed on the outer periphery of the second coupling member.
15. The rotor for a motor as claimed in claim 12, with the
positioning portion including a plurality of rugged faces formed on
the outer periphery of the second coupling member.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a rotor for a motor and,
more particularly, to a rotor for a motor of inner rotor type.
[0003] 2. Description of the Related Art
[0004] Motors generally include outer rotor type and inner rotor
type that is superior to outer rotor type in rotational stability.
Thus, inner rotor type motors are superior to outer rotor type
motors in fulfilling the needs of heat dissipation in the design
trends of high speed, integration of functions, and
miniaturization.
[0005] There is a plurality of conventional inner rotor type
motors. FIG. 1 shows a conventional rotor 5 for an inner rotor type
motor. The rotor 5 includes a shaft 51 and a magnet 52. The magnet
52 includes a central axial hole 521 through which the shaft 51
extends. The shaft 51 can be in tight coupling with the central
axial hole 521 of the magnet 52. However, the magnet 52 is liable
to break. In another approach, the shaft 51 is bonded by adhesive
to the central axial hole 521 of the magnet 52. However, the
adhesive is liable to lose its adhesiveness due to deterioration,
resulting in disengagement or undesired rotation of the magnet 52
from or relative to the shaft 51.
[0006] FIG. 2 shows a conventional rotor 6 for an inner rotor type
motor disclosed in Taiwan Patent Application No. 97104952. The
rotor 6 includes a shaft 61, a plurality of magnet retaining plates
62, at least two magnets 63, and two washers 64. The magnet
retaining plates 62 are stacked around the outer periphery of the
shaft 61 and each have at least two retaining grooves 621 for
securely receiving the magnets 63. The washers 64 sandwich the
magnet retaining plates 62 and the magnets 63. Due to the
arrangement of the magnet retaining plates 62 and the washers 64,
the magnets 63 will not disengage from the shaft 61. However, the
rotor 6 solves the disadvantages of the rotor 5 at the cost of
complicated structure, resulting in inconvenience in assembly.
[0007] FIG. 3 shows a conventional rotor 7 for an inner rotor type
motor disclosed in Taiwan Patent Application No. 971178192. The
rotor 7 includes a shaft 71, a magnet 72, and two fixing seats 73.
The magnet 72 includes a central axial hole 721 through which the
shaft 71 extends. The fixing seats 73 are in tight coupling with
the shaft 71 and sandwich the magnet 72, fixing the magnet 72 in a
predetermined location. By the arrangement of the fixing seats 73,
the magnet 72 is prevented from disengaging from the shaft 71.
However, the fixing seats 73 for sandwiching and fixing the magnet
72 cause limitation in the compact design of the rotor. Namely, the
rotor 7 is still complicated and inconvenient to assemble.
[0008] FIG. 4 shows a conventional rotor 8 for an inner rotor type
motor disclosed in Taiwan Patent Application No. 97135497. The
rotor 8 includes a shaft 81 and a plastic magnet 82. The shaft 81
includes an outer periphery having a positioning portion 811. The
plastic magnet 82 is formed by injection molding to envelop the
outer periphery of the shaft 81 with an inner periphery of the
plastic magnet 82 engaged with the positioning portion 811.
Although enhanced engaging stability is provided between the shaft
81 and the plastic magnet 82, the outer periphery of the rotor 8
must be processed to form the positioning portion 811, leading to
inconvenience in manufacturing of the rotor 8. Furthermore, the
engaging area provided by the positioning portion 811 is limited.
Namely, the resultant engaging stability between the plastic magnet
82 and the shaft 81 is still insufficient.
[0009] FIG. 5 shows a conventional rotor 9 for an inner rotor type
motor disclosed in Chinese Patent Publication Application No.
CN201118294. The rotor 9 includes a magnetic hub 91, an engaging
member 92, and a shaft 93. The magnetic hub 91 and the shaft 93 are
placed in a mold to form the engaging member 92 by injection
molding. Thus, the engaging member 92 is integrally formed with the
magnetic hub 91 and the shaft 93 as a single monolithic member to
prevent disengagement therebetween. However, the engaging member 92
is liable to deform due to overheating during high speed rotation
of the rotor 9, resulting in poor rotational balance as well as
disengagement between the magnetic hub 91, engaging member 92, and
shaft 93. Thus, the overall engaging stability of the rotor 9 is
still insufficient. Thus, a need exists for an improved rotor that
overcomes the disadvantages encountered during actual use of the
conventional rotors 5, 6, 7, 8, and 9.
SUMMARY OF THE INVENTION
[0010] An objective of the present invention is to provide a rotor
for a motor that provides enhanced engaging stability between the
shaft and the plastic magnet.
[0011] Another objective of the present invention is to provide a
rotor for a motor that can be assembled more easily.
[0012] A further objective of the present invention is to provide a
rotor for a motor that has less complicated structure.
[0013] The present invention fulfills the above objectives by
providing a rotor for a motor including a shaft having an outer
periphery with an engaging portion. A first coupling member
includes an engaging hole. The shaft extends through the engaging
hole of the first coupling member. The first coupling member is
engaged with the engaging portion of the shaft by tight coupling. A
plastic magnet envelops the shaft and the first coupling member by
injection molding.
[0014] Preferably, the outer periphery of the first coupling member
includes a positioning portion such that the first coupling member
has non-circular cross sections perpendicular to an axial direction
of the first coupling member. The plastic magnet is engaged with
the positioning portion. The positioning portion can include a
plurality of recessed portions, protruded portions, or rugged faces
formed on an outer periphery of the first coupling member.
[0015] Preferably, the plastic magnet integrally envelops an
intermediate portion of the shaft.
[0016] Preferably, the engaging portion of the shaft has an outer
diameter perpendicular to an axial direction of the shaft. The
engaging hole of the first coupling member has a diameter
perpendicular to the axial direction of the shaft. The diameter of
the engaging hole of the first coupling member is smaller than the
outer diameter of the engaging portion of the shaft.
[0017] Preferably, the rotor further includes a second coupling
member having an engaging hole. The shaft extends through the
engaging hole of the second coupling member. The second coupling
member is engaged with the engaging portion of the shaft by tight
coupling. The second coupling member is spaced from the first
coupling member in an axial direction of the shaft.
[0018] Preferably, the first and second coupling members are metal
rings that are less hard than the shaft.
[0019] The present invention will become clearer in light of the
following detailed description of illustrative embodiments of this
invention described in connection with the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] The illustrative embodiments may best be described by
reference to the accompanying drawings where:
[0021] FIG. 1 shows a cross sectional view of a conventional rotor
for a motor.
[0022] FIG. 2 shows a cross sectional view of another conventional
rotor for a motor.
[0023] FIG. 3 shows a cross sectional view of a further
conventional rotor for a motor.
[0024] FIG. 4 shows a cross sectional view of still another
conventional rotor for a motor.
[0025] FIG. 5 shows a cross sectional view of yet another
conventional rotor for a motor.
[0026] FIG. 6 shows an exploded, perspective view of a shaft and a
coupling member of a rotor for a motor of a first embodiment
according to the present invention.
[0027] FIG. 7 shows a cross sectional view of the rotor of the
first embodiment after assembly.
[0028] FIG. 8 shows an exploded, perspective view of a shaft and a
coupling member of a rotor for a motor of a second embodiment
according to the present invention.
[0029] FIG. 9 shows a cross sectional view of the rotor of the
second embodiment after assembly.
[0030] FIG. 10 shows an exploded, perspective view of the shaft and
another coupling member of the rotor for the motor of the second
embodiment according to the present invention.
[0031] FIG. 11 shows an exploded, perspective view of the shaft and
another coupling member of the rotor for the motor of the second
embodiment according to the present invention.
[0032] FIG. 12 shows an exploded, perspective view of a shaft and
two coupling members of a rotor for a motor of a third embodiment
according to the present invention.
[0033] FIG. 13 shows a cross sectional view of the rotor of the
third embodiment after assembly.
[0034] All figures are drawn for ease of explanation of the basic
teachings of the present invention only; the extensions of the
figures with respect to number, position, relationship, and
dimensions of the parts to form the preferred embodiments will be
explained or will be within the skill of the art after the
following teachings of the present invention have been read and
understood. Further, the exact dimensions and dimensional
proportions conforming to specific force, weight, strength, and
similar requirements will likewise be within the skill of the art
after the following teachings of the present invention have been
read and understood.
[0035] Where used in the various figures of the drawings, the same
numerals designate the same or similar parts. Furthermore, when the
terms "first", "second", "inner", "outer", "side", "portion",
"section", "axial", "annular", and similar terms are used herein,
it should be understood that these terms refer only to the
structure shown in the drawings as it would appear to a person
viewing the drawings and are utilized only to facilitate describing
the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0036] With reference to FIGS. 6 and 7, a rotor 1 for a motor of a
first embodiment according to the present invention includes a
shaft 11, a coupling member 12, and a plastic magnet 13. The shaft
11 and the coupling member 12 are tightly engaged with each other.
The plastic magnet 13 integrally envelops the shaft 11 and the
coupling member 12. The coupling member 12 prevents the plastic
magnet 13 from disengaging from the shaft 11.
[0037] The shaft 11 can be a rod made of stainless steel. The shaft
11 includes an outer periphery having an engaging portion 111. The
engaging portion 111 has an outer diameter D1 perpendicular to an
axial direction of the shaft 11.
[0038] The coupling member 12 can be a metal ring that is less hard
than the shaft 11. As an example, the coupling member 12 can be an
annular member made of copper such that the shaft 11 is less likely
to be damaged by the coupling member 12 when the coupling member 12
is engaged with the shaft 11 by tight coupling. Furthermore, the
coupling member 12 includes an engaging hole 121 extending from a
side through the other side of the coupling member 12. Further, the
engaging hole 121 has a diameter D2 perpendicular to the axial
direction of the shaft 11. The diameter D2 of the engaging hole 121
is slightly smaller than the outer diameter D1 of the engaging
portion 111 of the shaft 11. Thus, when the coupling member 12 is
mounted around the engaging portion 111 of the shaft 11 with the
shaft 11 extending through the engaging hole 121, the coupling
member 12 and the shaft 11 can be more reliably engaged with each
other through tight coupling.
[0039] The plastic magnet 13 can be made of plastic material mixed
with magnetic powders. After the coupling member 12 is tightly
engaged with the shaft 11, the coupling member 12 and the shaft 11
are placed in a mold, and the plastic magnet 13 is formed by
injection molding to simultaneously envelop the coupling member 12
and an intermediate portion of the shaft 11.
[0040] By such an arrangement, since the coupling member 12 is
tightly engaged with the engaging portion 111 of the shaft 11
beforehand, the plastic magnet 13 can engage with the shaft 11
after the plastic magnet 13 integrally envelops the shaft 11 and
the coupling member 12. Furthermore, due to coupling between the
plastic magnet 13 and the coupling member 12, the plastic magnet 13
is prevented from moving axially on or disengaging from the shaft
11. Thus, enhanced engaging stability is provided between the shaft
11, the coupling member 12, and the plastic magnet 13.
[0041] With reference to FIGS. 8 to 11, similar to the rotor 1 of
the first embodiment, a rotor 2 for a motor of a second embodiment
according to the present invention includes a shaft 21 with an
engaging portion 211, a coupling member 22 with an engaging hole
221, and a plastic magnet 23. The difference between the rotor 2 of
the second embodiment and the rotor 1 of the first embodiment is
that the coupling member 22 includes an outer periphery having a
positioning portion 222 such that the engaging member 22 has
non-circular cross sections perpendicular to an axial direction of
the coupling member 22 for engagement with the plastic magnet 23.
Examples of the positioning portion 222 include recessed portions
(such as grooves, depressions, or holes) as shown in FIGS. 8 and 9,
protruded portions (such as ribs or protrusions) as shown in FIG.
10, or rugged faces (such as knurls) as shown in FIG. 11, on the
outer periphery of the coupling member 22. In this embodiment, the
positioning portion 222 includes a plurality of annularly spaced
grooves formed in an outer periphery of the coupling member 22.
[0042] By the above technical feature, the coupling member 22 of
the rotor 2 of the second embodiment has non-circular cross
sections due to provision of the positioning portion 222. Thus, the
plastic magnet 23 engages with the positioning portion 222 when the
plastic magnet 23 integrally envelops the coupling member 22 and
the intermediate portion of the shaft 21. Thus, the coupling member
22 not only prevents the plastic magnet 23 from moving axially or
disengaging from the shaft 21, but also prevents the plastic magnet
23 from rotating relatively to the shaft 21, providing further
enhanced positioning effect in the axial direction.
[0043] With reference to FIGS. 12 and 13, similar to the rotor 1 of
the first embodiment, a rotor 3 for a motor of a third embodiment
according to the present invention includes a shaft 31 with an
engaging portion 311, a coupling member 32 with an engaging hole
321, and a plastic magnet 33.The difference between the rotor 3 of
the third embodiment and the rotor 1 of the first embodiment is
that the rotor 3 includes a plurality of coupling members 32 spaced
in the axial direction of the shaft 31. The plastic magnet 33
simultaneously and integrally envelops the intermediate portion of
the shaft 31 and the coupling members 32.
[0044] By the above technical feature, compared to the rotor 1 of
the first embodiment, the engaging area between the plastic magnet
33 and the coupling members 32 of the third embodiment is increased
after the plastic magnet 33 of the rotor 3 integrally envelops the
shaft 31 and the coupling members 32, providing the plastic magnet
33 with further enhanced engaging effect. Thus, disengagement of
the plastic magnet 33 from the shaft 31 is further avoided.
[0045] According to the above, the rotors 1, 2, 3 of the present
invention use the plastic magnets 13, 23, 33 that are made of
plastic material mixed with magnetic powders and that are formed by
injection molding to simultaneously envelop the shafts 11, 21, 31
and at least one coupling member 12, 22, 32, achieving several
effects.
[0046] Firstly, the present invention provides rotors 1, 2, 3 for a
motor in which the plastic magnets 13, 23, 33 are prevented from
moving axially or disengaging from the shafts 11, 21, 31 when the
plastic magnets 13, 23, 33 simultaneously envelop the shafts 11,
21, 31 and the coupling members 12, 22, 32, providing enhanced
engaging stability. This is because the coupling members 12, 22, 32
have been tightly engaged with the engaging portions 111, 211, 311
of the shafts 11, 21, 31 beforehand.
[0047] Secondly, the present invention provides rotors 1, 2, 3 for
a motor that can be assembled by simply engaging the coupling
members 12, 22, 32 with the engaging portions 111, 211, 311 of the
shafts 11, 21, 31 by tight coupling and then by injection molding
to make the plastic magnets 13, 23, 33 simultaneously envelop the
shafts 11, 21, 31 and the coupling members 12, 22, 32. The whole
assembling process is easy, and assembling convenience is
enhanced.
[0048] Thirdly, the present invention provides rotors 1, 2, 3 for a
motor that merely includes the shafts 11, 21, 31, the coupling
members 12, 22, 32, and the plastic magnets 13, 23, 33. The whole
structure is simple, reducing structural complexity.
[0049] Thus, since the invention disclosed herein may be embodied
in other specific forms without departing from the spirit or
general characteristics thereof, some of which forms have been
indicated, the embodiments described herein are to be considered in
all respects illustrative and not restrictive. The scope of the
invention is to be indicated by the appended claims, rather than by
the foregoing description, and all changes which come within the
meaning and range of equivalency of the claims are intended to be
embraced therein.
* * * * *